This application is based on and claims priority from Japanese Patent Application No. 2002-18969 filed on Jan. 28, 2002, the content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a multi-piece rim used for wheels mounted on construction vehicles and the like.
2. Description of the Related Art
In a wheel of a large-sized construction vehicle, since a tire has a high rigidity, a multi-piece rim is usually used for mounting the tire so as to facilitate mounting and demounting of the tire.
FIGS. 6-8 illustrate a structure of a conventional multi-piece rim. As illustrated in FIG. 8, the conventional multi-piece rim includes (1) an annular rim base 1 which includes a first, back flange 2 and a gutter band 8, (2) a bead seat band 9 which is mounted radially outside the gutter band 8 and includes a second flange 3, (3) a lock ring 6 which has one slit in a circumferential direction and prevents the bead seat band 9 from moving axially outwardly from gutter band 8, and (4) first and second side rings 4 and 5 which are axially supported by the first flange 2 and the bead seat band 9, respectively, although slightly movable in an axial direction of the multi-piece rim. A tire 7 is mounted axially inboard of the side rings 4 and 5.
As illustrated in FIGS. 6 and 7, a contact surface of the first flange 2 with the first side ring 4 and a contact surface of the second flange 3 with second the side ring 5, respectively, extend in a direction perpendicular to the axial direction of the multi-piece rim. In order to facilitate mounting of the side rings 4 and 5, a radial clearance C is provided radially between the first side ring 4 and rim base 1, and a radial clearance Cxe2x80x2 is provided radially between the second side ring 5 and the bead seat band 9.
In the conventional multi-piece rim, due to the radial clearances C, Cxe2x80x2 provided radially inside the first and second side rings 4 and 5, and a rigidity difference between rim members, a small amount of mutual slippage is likely to occur between the rim members during running of the vehicle.
Especially in the case of a demountable rim which is directly coupled to a hub by a clamp, the mutual slippage in the radial direction and in the circumferential direction may repeatedly occur between the first side ring 4 and the rim base 1 and between the second side ring 5 and the bead seat band 9. This may cause the following problems:
(1) A bead portion of the tire may be damaged.
(2) A coated layer coated on a bead seat portion of the rim may be peeled off to cause a corrosion fatigue.
(3) Contact surfaces of the rim members may be damaged due to a fretting fatigue.
(4) Small cracks may be generated due to friction between the rim members.
(5) An O-ring may be damaged to cause air leakage.
As a result, the durability of the conventional multi-rim may be decreased.
In order to solve the above-described problems, the applicant previously proposed a multi-piece rim structure in Japanese Patent Examined Publication No. H4-4161. According to the proposed structure, the mutual slippage problem as described above can be solved, but the following problems still exist:
(a) First and second inclined surfaces must be formed in first and second side rings, respectively, resulting in an increase in cost.
(b) A relatively large amount of axial clearance needs to be provided between a side ring and a back flange. As a result, when the side ring is broken due to an axial force exerted on the rim, the side ring will collide with the back flange with a relatively high speed, accelerated due to the relatively large amount of the axial clearance, which may damage the back flange.
An object of the present invention is to provide a multi-piece rim which is durable and reliable, and can also reduce a mutual slippage between a first side ring and a first flange and/or between a second side ring and a second flange thereby suppressing a fretting fatigue.
The above-described object can be achieved by the present invention, as follows:
A multi-piece rim includes (a) a rim base which includes a first flange having a first stepped recess for inserting a tool therein and a gutter band, (b) a bead seat band which includes a second flange having a second stepped recess for inserting a tool therein, (c) a lock ring, and (d) a first side ring located on a side of the first flange and a second side ring located on a side of the second flange.
The first side ring includes a radially extending, axially outboard side surface, and a circumferentially extending inner surface which includes a tapered surface and a non-tapered surface located axially inboard of the tapered surface.
The second side ring includes a radially extending, axially outboard side surface, and a circumferentially extending inner surface which includes a tapered surface and a non-tapered surface located axially inboard of the tapered surface.
The first flange of the rim base includes a radially extending, axially inboard surface, axially opposing the radially extending side surface of the first side ring, and a circumferentially extending surface radially contacting the tapered surface of the circumferentially extending inner surface of the first side ring. The second flange of the bead seat band includes a radially extending, axially inboard surface, axially opposing the radially extending side surface of the second side ring, and a circumferentially extending surface radially contacting the tapered surface of the circumferentially extending inner surface of the second side ring.
The circumferentially extending surface of the first flange and the tapered surface of the circumferentially extending inner surface of the first side ring are inclined radially outwardly in an axially outboard direction of the multi-piece rim.
An axial clearance is provided between the radially extending surface of the first flange and the radially extending side surface of the first side ring. The axial clearance has a magnitude equal to or less than about 15 mm, and more preferably, a magnitude of about 2 to about 4 mm.
The radially extending surface of the first flange and the radially extending side surface of the first side ring may contact each other.
The circumferentially extending surface of the first flange and the tapered surface of the circumferentially extending inner surface of the first side ring are inclined by about 10 to about 35 degrees with respect to an axial direction of the multi-piece rim.
The circumferentially extending surface of the second flange and the tapered surface of the circumferentially extending inner surface of the second side ring are inclined radially outwardly in an axially outboard direction of the multi-piece rim.
A second axial clearance is provided between the radially extending surface of the second flange and the radially extending side surface of the second side ring. The second axial clearance has a magnitude equal to or less than about 15 mm, and more preferably, a magnitude of about 2 to about 4 mm.
The radially extending surface of the second flange and the radially extending side surface of the second side ring may contact each other.
The circumferentially extending surface of the second flange and the tapered surface of the circumferentially extending inner surface of the second side ring are inclined by about 10 to about 35 degrees with respect to the axial direction of the multi-piece rim.
In the multi-piece rim according to the present invention, since the circumferentially extending surface of the first flange and the tapered surface of the circumferentially extending inner surface of the first side ring and/or the circumferentially extending surface of the second flange and the tapered surface of the circumferentially extending inner surface of the second side ring are inclined radially outwardly in the axially outboard direction of the multi-piece rim, frictional forces generated between rim members when a tire pressure acts on the side rings are increased to suppress a circumferential slippage between the rim members. As a result, a fretting fatigue due to the mutual slippage between the rim members is effectively suppressed.
Further, since the axial clearance of the magnitude equal to or less than about 15 mm, more preferably, the magnitude of about 2 to about 4 mm is provided between the radially extending surface of the first flange and the radially extending side surface of the first side ring and/or between the radially extending surface of the second flange and the radially extending side surface of the second side ring, even if the side rings are broken, the side rings will collide with the flanges and stop before a moving speed of the side rings is accelerated. Thus, the flanges will not be broken and the side rings will be prevented from moving axially outwardly from the multi-piece rim.
In the case where the radially extending surface of the first flange and the radially extending side surface of the first side ring and/or the radially extending surface of the second flange and the radially extending side surface of the second side ring contact each other, even if the side rings are broken, the side rings will not move axially outboard. Thus, the flanges will not be broken. Further, due to the frictional force between the contact surfaces, a circumferential slippage between the rim members will be effectively suppressed.